House Extensions Hertford

An extension in Hertford is judged against a district plan, and in three wards against a neighbourhood plan on top of it. The ground under your garden changes across the town. We build the extension and coordinate the structural engineer, the applications and the inspections.

For Hertford, on London-derived ranges a single-storey rear extension typically starts from £40,000, or £2,000 to £2,800 per m²; Hertfordshire work generally runs below that. GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Hertford: the structural engineer we appoint designs the structure, we build it, and building control signs it off.

Which plans your extension is judged against

East Herts District Council is the local planning authority for Hertford. It adopted its District Plan on 23 October 2018, for the period 2011 to 2033, and that is the starting point for any application.

Three Hertford wards have made neighbourhood plans of their own: Bengeo and Sele in July 2021, and Kingsmead on 26 July 2023. A fourth area, Hertford Castle Plus, covering Castle, Kingsmead West and Bengeo South, was designated in July 2024, and that plan has not yet been made. Which ward you are in decides whether there is a second layer of policy to answer.

Housing in Hertford

Of the 14,040 homes the valuation list records in Hertford, 16% were built before 1919, 9% between the wars and 74% since 1945; 31% are flats and 69% are houses. 33% of homes here are terraced; a rear extension on a terrace in Hertford digs foundations close to both neighbours, so notices to both are normal.

A neighbourhood plan rule that caps your roof height

In Kingsmead, roof height is capped by policy. Kingsmead neighbourhood plan policy HKBE4 requires rooflines of development in residential areas to be limited to the height of the homes immediately adjacent or opposite.

For a two storey rear extension in that ward, that is a constraint to design to before drawings are submitted. We work to it from the first sketch, so the scheme that goes in is the scheme that can be built.

What is under your garden

Under the built up part of Hertford the bedrock is chalk. British Geological Survey 1:50,000 mapping shows it as the Lewes Nodular Chalk Formation and Seaford Chalk Formation, undifferentiated. The south east of the town is the exception, where the Lambeth Group of clay, silt and sand comes to bedrock. That includes the south east end of Mangrove Road, the southern part of Balls Park, London Road and Foxholes Business Park.

Groundworks in the historic core can also meet archaeological interest. The county Historic Environment Record holds about 350 records within Hertford Conservation Area. Foundation depths and trial holes are set by the engineer for your address, and we build to that design.

Water and trees before you dig

Water is a standing constraint in Hertford. The Environment Agency runs four separate flood warning areas that name the town, one for each river. They are the River Beane at Hertford, the River Lee at Hertford and Ware, the River Rib at Wadesmill to Hertford, and the River Mimram from Tewin to Hertford. The Kingsmead neighbourhood plan also attributes drainage pressure in that ward in part to Victorian and Edwardian properties having been substantially extended since its two ditches were designed.

Trees carry their own timetable. You must give the council six weeks notice under section 211 before carrying out work to a tree in a conservation area that is not already covered by a Tree Preservation Order. That notice sits at the front of the programme, not in the middle of it.

Kitchen extensions in Hertford

48% of the houses in Hertford are terraced. On a terrace the kitchen extension is built out from the back, into the side return where the house has one or across the full rear width, and a steel beam takes the old back wall so the kitchen and the new room become one space. The fit-out is priced on its own page, kitchen renovation in Hertford; the build figures are in the table above.

Side return extensions in Hertford

Side returns belong to Victorian and Edwardian terraces, and only 16% of homes in Hertford predate 1919, so they are the exception here; most extensions run across the full rear width instead. Our side return extension page covers the build in detail, with build rates of £2,400 to £3,200 per m².

Double storey extensions in Hertford

Under permitted development a two-storey rear extension can go no more than 3 metres beyond the original rear wall and must stay at least 7 metres from the rear boundary, and in a conservation area it is not permitted development at all. Many gardens are too short for the 7 metre rule, so a double storey extension in Hertford often needs planning permission from East Herts District Council. On the 33% of homes that are terraced, the neighbours' windows usually decide the depth. Our double storey extension page explains the build, at £1,800 to £2,600 per m² across both floors.

• Steel goalpost frames where the rear wall opens up
• Planning applications and permitted development assessments
• Building control inspections at foundation, damp course and steel stages

VOA Council Tax stock of properties, March 2025, for Hertford Bengeo, Hertford West, Hertford Foxholes and Hertford South. Counts rounded by the VOA.

When comparing house extensions in Hertford with other work, it helps to read RSJ and steel beam installation in Hertford, house extensions in Ware, basement extensions, a garage conversion instead, house extensions anywhere in London and Crittall Doors Guide.

The GS Renovation Difference in Hertford

An extension here has three approval questions running at once: the district plan, any neighbourhood plan for your ward, and building regulations. Getting those in the right order is most of the job. We appoint the structural engineer, coordinate the building control application and inspections, and build to the calculations issued. One point of contact from the first survey to the final inspection, fully insured, with a free quotation and no obligation.

• Programme planned around party wall notice periods before excavation near a neighbour
• Registered in England, Companies House no. 14611254
• Garden levels and access made good where the build meets outside

Reviewed jobs near Hertford

1 MyBuilder review from Hertford, with each customer's own job title:

• Tile kitchen splash back, Hertford, 18 Jul 2021 (5 out of 5)

Read all 31 on our reviews page.

Checked by Abdelaaziz Saaid, founder and director of GS Renovation Ltd (Companies House no. 14611254). Structural design is by the consulting engineer appointed to your project.